Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$207.40	7.745%	$223.4631	$223.46	$223.45	$223.50
Purchase #2	$14.87	6.170%	$15.7875	$15.79	$15.80	$15.80
Purchase #3	$33.57	10.377%	$37.0536	$37.05	$37.05	$37.10
Purchase #4	$176.90	7.659%	$190.4488	$190.45	$190.45	$190.40
Purchase #5	$158.60	8.427%	$171.9652	$171.97	$171.95	$172.00
Purchase #6	$58.98	10.345%	$65.0815	$65.08	$65.10	$65.10
Purchase #7	$54.90	12.280%	$61.6417	$61.64	$61.65	$61.60
7 purchase totals =	$705.22		$765.4414	$765.44	$765.45	$765.50